1. Field
Example embodiments relate to a memory device heat treatment method, and more particularly, to a memory device that can improve a data retention characteristic of a memory device and a thermal treatment method thereof.
2. Description of Related Art
Currently, a non-volatile semiconductor memory is being widely used as one of various types of storage that can continuously store previously stored information even when power is shut off. A representative example of a non-volatile memory may be a flash memory. In comparison to a conventional Hard Disk Drive (HDD), the size of the flash memory may be small. The flash memory may consume a smaller amount of power and improve a read speed. Currently, a solid state disk (SSD) using a large amount of flash memory is offered as a replacement for the HDD.
Representative examples of the flash memory may include a NAND flash memory, a NOR flash memory, and the like. A NAND scheme and a NOR scheme may be distinguished based on a configuration of a cell array and an operational scheme of the cell array.
The flash memory may include a plurality of memory cells. A single memory cell may store at least one data bit. The single memory cell may include a control gate and a floating gate. An insulator may be inserted between the control gate and the floating gate. The insulator may be inserted between the floating gate and a substrate. A process of storing data in a memory cell of the flash memory may be referred to as a “program”. A process of erasing the program or the data may be performed by a hot carrier effect or a Fowler-Nordheim (F-N) tunneling mechanism.
Under a particular bias condition, a channel may be formed in the nearest region to the floating gate, among a substrate region. The channel may be a region that is generated when minority carriers of the substrate region cluster together. It may be possible to control the minority carriers to program data to the memory cell or erase the data from the memory cell.
When a particular bias is applied to a source, a drain, and the control gate of the substrate region, the minority carriers of the channel may move to the floating gate. Representative mechanisms of moving the minority carriers to the floating gate may include the hot-carrier effect and the F-N tunneling mechanisms.
The hot-carrier effect mechanism may move relatively many carriers to the floating gate within a quicker period of time than the F-N tunneling mechanism, whereas the hot-carrier effect mechanism may cause great physical damage to the insulator between the floating gate and the substrate. The F-N tunneling mechanism may cause relatively little damage to the insulator, however, the F-N tunneling mechanism may not disregard the damage occurring when a number of times that data is programmed to and erased from a memory cell is increased.
When carriers are accumulated in the floating gate to thereby form charges, data of the memory cell may be determined from the charges. When the insulator around the floating gate is physically damaged, a carrier leakage path may be formed in the insulator. When charges stored in the floating gate are lost via the leakage path, the data stored in the memory cell may be destroyed. Accordingly, research is being conducted regarding a method that may control or recover the physical damage to the insulator around the floating gate.